1. Field of the Invention
The present invention relates generally to a device and a method for reducing polarization-dependent effects in dynamical optical components based on surface modulation of a polymer gel or membrane, and specially to a device and method that modifies, removes or leads away unwanted reflections from incident light or information carrier communicating with said optical component.
2. Description of the Related Technology
The high cost of components, in particular for the more advanced components including many subparts, is slowing down the deployment of optical communication systems and the introduction of all-optical networks. Consequently, it is necessary to develop cost effective components that have the necessary specifications, but allow low-cost assembly and production methods to be used.
Dynamic or tunable components are of particular demand in fiber optic communication systems and the modules that such systems comprise. A performing, low-cost, and highly scalable dynamic optical component based on surface modulation of a polymer gel (or membrane) is documented in the Norwegian patent application no. 2002 4265.
The state of polarization of the light in an optical communication system fluctuates over time due to environmental effects on the system components (especially the optical fiber) and changes in the topography of the system. The performance of both the individual components and the modules that the system is built from, should therefore be as independent of the polarization state of the incoming light as possible, and change the polarization state as little as possible. These requirements ensure maximum transmission distance, maximum rate of information that can be transferred, and maximum number of nodes that can be passed in a network.
Several optical systems have been suggested for tunable diffraction gratings with applications to fiber optical components. One of the known methods is diffractive MEMS (D-MEMS) from companies like Light Connect and Silicon Light Machines.
These devices are based on a moveable diffraction grating consisting of at least two separate pieces. There are provided a stationary reflective bottom surface, and a moveable set of thin blades, the grating, that are made of etched silicon. The blades can be moved up and down by the application of an appropriate electrical field. The result is a diffraction grating, where the effective phase shift of the grating is given by the relative position of the blades and the reflective surface below. This arrangement can be used to make effective variable optical attenuators, but the set of blades must be processed out of silicon. This is an expensive process, and the yield of the process goes dramatically down as the system size increases. Components made from D-MEMS are hence effective and performing, but expensive.
U.S. Pat. No. 3,527,522 discloses a light-modulating device comprising a glass prism attached with a reflection free glass backing plate, a transparent electrode and a deformable material such as silicon rubber. A substrate with addressable electrodes is arranged in parallel with the surface of said deformable silicon rubber with an air gap between the material and the substrate.